This invention relates to a dry type discharge liquid extraction apparatus by means of which gases or liquids generated in a human body cavity after operation on a human body, particuarly thoracotomic operations, may be discharged for an extended time at a constant pressure.
The prior extraction apparatus used for discharging gases or liquids from the body cavity may be classified into the following two types. One is a wet type apparatus in which a suction pressure adjustment chamber having a liquid column is connected to a suction source for realizing a constant suction pressure. The other is a dry type apparatus provided with a suction pressure adjustment mechanism, in place of the suction pressure adjustment chamber having a liquid column, with the initially discharged liquid being stored in a sealing chamber for liquid sealing; or another dry type apparatus having no suction pressure adjustment function and connected to an adjustable suction source, with the initially discharged liquid being likewise stored in the liquid seal chamber for liquid sealing.
In a majority of the conventional wet type apparatus, there is provided a suction adjustment chamber and a liquid seal chamber to prevent reverse flow of the gas and liquid towards the body cavity, so that the extraction apparatus may be employed advantageously in a hospital room devoid of an adjustable suction source. However, such apparatus has the disadvantage that an accurate amount of liquid must be supplied to realize the water levels required in the suction adjustment chamber and the liquid seal chamber all at the busy time after the operation. In addition, when an elevated negative pressure is generated in the body cavity and the liquid in the seal chamber is sucked into the body cavity tube, provided that the elevated negative pressure in the body cavity is not decreased by some reason as in case of a valvular pneumothorax, the negative pressure acts continuously on the liquid sucked from the body cavity, so that the sucked liquid may remain in the tube. In such case, outside air may be passed through the liquid in the suction pressure adjustment chamber and discharged from the apparatus through the nozzle, so that discharge liquid cannot be extracted from the body cavity.
The conventional dry type extraction apparatus may be classified into two groups, with one having a suction pressure adjusting mechanism and making use of pneumatic pressure with the initially discharged liquid being stored so as to be used as sealing liquid. The extraction apparatus of this kind requires a complicated structure and a tube connection between the main member and the suction pressure adjusting mechanism provided outside of the main member. Accordingly, there is a necessity for providing positive sealing at each of the connecting portions. Since the liquid seal chamber is connected directly by a tube or the like to a body cavity tube, if an elevated negative pressure is generated in the body cavity, liquid may flow from the liquid seal chamber into the body cavity as reverse flow, thus occasionally destroying the liquid seal. If a slack exists in the body cavity tube, the reserved flow may remain in the lower part of the slack and operate as secondary manometer, thus causing changes in the suction pressure. The other dry type apparatus is provided with no suction pressure adjusting mechanism and is instead connected to an outside adjustable suction source with the initally discharged liquid being used as sealing liquid in the liquid sealing chamber. In such case, there is the disadvantage that an adjustable suction source must be provided in the hospital chamber or a specified suction pressure adjusting mechanism must be annexed to the extraction apparatus. In such kind of extraction apparatus, there is again the risk of destruction of liquid extraction apparatus, there is again the risk of destruction of liquid sealing caused by reverse liquid flow from the liquid seal chamber into the body cavity caused by an elevated negative pressure in the body cavity and the secondary manometer phenomenon described above. In these two dry type extraction apparatus, a one-way ventilation valve is provided between the liquid sealing chamber and the suction source nozzle so as to be opened only in the direction of the suction source, and an elevated negative pressure is established in the body cavity. The problem of the liquid in the liquid sealing chamber remaining in the cavity tube and of the inhibition of suction is more severe than that in the wet type apparatus, because there is no air inlet from outside of the extraction apparatus by the operation of the one-way ventilation valve. Disadvantages common to the two existing dry type apparatus are that the allowable maximum levels of suction pressure and the negative pressure generated in the body cavity cannot be adjusted to accomodate the condition of the patient, and that the suction pressure is unstable in that it cannot adjust automatically with the unexpected fluctuations in the suction pressure occurring in the hospital piping system which may be in the range of, e.g., -60 to -180 cm. of water.